Centos 5.5 + Ispconfig 3 fresh install problems

Hi all.
I'm a beginner when it comes to Unix based OS-s. My friend has lost his server due to HDD failure and asked me to help him configure a new one. He had W-Xp as OS and i think Xampp or Wampp for the webserver side. I told him that i found a great tutorial with Centos and Ispconfig3 which would make his life easier and more secure . So i followed the instruction from this website and finally wanted to test the server but i does not work . We have a fixed IP (external) from the ISP, and we don't use a router. During the installation i set up this fixed ip as the ip of the eth0 network controller, the subnet mask, the gateway, and 2 DNS servers which the ISP gave us. First Question: how important is the hostname ? i mean I entered as the hostname : "server.mysite.com" (mysite.com is an example). Is this ok? Then i finished the installation and logged into ISPconfig.
Server Services: servername is "server.mysite.com" but this is also my hostname Is that bad?
In System/ Server config i can see my IP,netmask, gateway and my hostname which is "mysite.com". Those Nameservers should be those which the ISP gave us (2 DNS servers) or our own nameservers?
At DNS tab , i added a zone with the DNS wizard. Domain "mysite.com", nameservers "ns.mysite.com" and "ns1.mysite.com" and the server's IP. Then in records i added two A records with the two nameservers (the nameservers having our server's IP). So the nameservers and the server have the same IP cause we want to use our own nameservers on the same pc.
After his server died, he didn't change anything at his domain registrar, so the IP remained the same , and he had 1 nameserver the "ns.mysite.com" version.
I restarted the server, there were no errors, but when i typed www.mysite.com nothing happened. We can access our server if we type the IP number in the browser, but it does not work when typing the domain name.
What are we doing wrong? probably everything )
Sorry for the stupid questions.
If anyone has some kind of advice it would be greatly appreciated

At DNS tab , i added a zone with the DNS wizard. Domain "mysite.com", nameservers "ns.mysite.com" and "ns1.mysite.com" and the server's IP. Then in records i added two A records with the two nameservers (the nameservers having our server's IP). So the nameservers and the server have the same IP cause we want to use our own nameservers on the same pc.

Click to expand...

These tutorials (although they are fro ISPConfig 2) should give you the idea:

Create an A record where? in ISPConfig? i can't create any records at the domain registrar. When i log in to the domain registrar i have only a few options. Actually i have only one option ) add the nameservers and their IP. Nothing more. i can't add A records or MX records or any records. Just the nameservers name in "ns.domain.com" format and their IP addresses.
As i pointed out in my first post, nothing changed at the domain registrar after the server died, the nameserver remained the same and also the ip that's why i think I'm doing something wrong in setting up the server. I read something about that hen <> egg "thing" when the nameserver is on the same server, and how to resolve this issue with glue records at the domain registrar, but i don't have these kind of options.
What are my options if i give up the idea of using our own nameservers? Should i register on some freedns site and use their nameservers for our domain? But it's so much cooler if u have your own nameserver with your company name & stuff

Nope. I can only change the nameservere and their IP. As i was looking for a free dnd server, searching for that trial software which was used for a dns server(on WinXP) before the server died, i read this : The registrar may do a DNS lookup to see if you have the DNS server name listed correctly on your DNS server. So before you use a new DNS servers name ("ns#.example.com") for the first time in a domain name registration, make sure to first setup an NS-record and associated A-record for this in ...............( <- software name). So, i was thinking to go on my domain registrars page, enter 2 new nameservers which i will make with my ispconfig, and maybe that will work. So when they do that DNS lookup they will see that the servers are working and then it will be ok, i think if not, then some free nameservers.
Thanks again.
Take care.